Bacterial & Fungal meningitis Flashcards
Basically what is meningitis?
- infection of CSF
- Acute fever, headache, neck stiffness +/- rash
- Fully conscious, no focal neuro signs -Usually viral can be bacterial
What is encephalitis?
- Infection of the brain tissue
- Acute fever, headache, neck stiffness
- Altered conscious level, seizures, +/- focal neuro signs
- Usually viral
- Herpes simplex most common
- All ages 1/2 in >50yrs
- Diagnosed by viral nucleic acid in CSF
What is a brain abscess?
- Abscess within brain tissue
- Insidious onset of fever, headache, +/- neck stiffness
- +/- altered conscious level, seizures, focal neuro signs
- Usually bacterial may be parasitic
How can micro-organism get into the brain/meninges?
- Blood-borne invasion (blood-brain barrier or blood-CSF barrier)
- Peripheral nerves
What type of meningitis is found in university students? How can it present?
- Neisseria meningitidis
- Natural habitat nasopharynx
- Septicaemia w/purpuric rash
- Septicaemia w/meningitis
- Pyogenic (purulent) meningitis w/no rash
- Fulminant septicaemia
What are factors allowing the intravascular survival and infection by N.meningitidis?
- Capsule: protects against complement-mediated bacteriolysis & phagocytosis
- Acquisition of iron from transferrin
- Able to cross blood-brain barrier & multiply in subarachnoid space
What are the clinical implications of meningococcal septicaemia?
- Echymoses
- Eyes w/intraocular haemorrhage
- Thrombosis & gangrene of the fingers
- Haemorrhagic adrenals
What is the treatment & prevention for Neisseria meningitidis?
T= penicillin, ceftriaxone, cefotaxime, early treatment, intensive care P= vaccination
Describe Haemophilus influenzae
- Unable to grow in absence of blood/ certain components
- Small, pleomorphic gram -ve cocco-bacilli
- Some strains produce a polysaccharide capsule
- Type B cause most invasive disease (meningitis)
How is Haemophilus influenzae treated?
- Ceftriaxone, cefotaxime, ampicillin
- Chemoprophylaxis of contacts of invasive disease= rifampicin
Describe strep pneumoniae
- Gram +ve cocci
- Cells in pairs
- Requires blood/serum for growth
- Normal habitat= human rest tract
- Transmission via droplet spread
- Optochin test
- All ages (more common in elderly & immunocompromised)
What is the treatment for strep pneumoniae?
- Ceftriaxone, cefotaxime, penicillin resistant
- Conjugate vaccine against common serotypes
Describe steroid use for meningitis in adults
- Dexamethasone 0.15mg/kg IV every 6 hours 2-4days
- Causes dec levels of vancomycin in CSF so use rifampicin as well
- Steroids for S.pneumoniae not meningococcal meningitis-no effect
- Given shortly before 1st dose of antibiotics
Describe neonatal meningitis
- Group B beta-haemolytic strep
- Escherichia coli
- Listeria monocytogenes
- Early onset usually septicaemia
- Late onset usually meningitis
- Treatment= cefotaxime, ampicillin & gentamicin
What are complications of meningitis?
- Death
- Overwhelming sepsis
- Raised intracranial pressure
- Deafness
- Delayed development
- Seizures
- Stroke
- Hydrocephalus
What are types of lymphocytic meningitis?
- Viral meningitis (enteroviruses, herpes simplex)
- Spirochete (treponema, borrelia)
- Polio can cause meningitis that can lead to paralysis
- TB meningitis (RF: alcoholic, immunocompromised, from endemic area)
Describe a brain abscess
- Usually bacterial
- Spread of organisms from adjacent structures (strep anaerobes from middle ear or sinuses)
- Bloodstream spread (staph aureus)
- Prolonged course of antibiotics
Describe cryptococcal meningitis
- Cryptococcus= yeast seen in CSF (w/indian ink stain)
- Common problem in late stage HIV
- Insidious onset
- Lymphocytic meningitis
- Prolonged treatment with amphotericin, flucytosine/fluconazole
What is Japanese encephalitis virus?
- Commonly affects children
- 1/3 die from acute illness, 1/3 severe neuro disability
- Vaccination available
What is rabies encephalitis?
- Common in many countries
- Dog,fox,bat bites
- 100% mortality
- Prevented by vaccine
Describe Clostridium tetani and its treatment
- Gram +ve spore forming bacilli (drumsticks)
- Strict anaerobe
- Widespread in soil
- Non-invasive but produces tetanospasmin
- Antitoxin (horse or human)
- Penicillin or metronidazole
- Drugs for spasm, muscle relaxants, resp support
- Prevention= toxoid
What is the mechanism of action of tetanus?
1) Toxin gene on plasmid is encoded into cell
2) Toxin spreads via bloodstream & retrograde transport
3) Binds to ganglioside receptors blocking release of inhibitory interneurones
4) Convulsive contraction of voluntary muscles
What are the signs &symptoms of tetanus?
- Lockjaw/trismus
- Tonic muscle spasms
- Opisthotnus
- Resp difficulties
- Cardio instability
- Sympathetic NS affected
How will the following change in a TB, Viral, bacterial & cryptococcus infection: Cell count Cell type Glucose levels Protein levels
- B: cc=INC(>200) ct= polymorphs g=DEC(2) p=INC
- V: cc=INC(20-200) ct=lymphocytes g=NORM/RED p=NORM/INC
